Layered Flask Cell Culture System

ABSTRACT

A multilayered cell culture apparatus for the culturing of cells is disclosed. The cell culture apparatus is defined as an integral structure having a plurality of flexible cell culture compartments in combination with a spacer material maintaining air space(s). The expandable compartments of the cell culture apparatus have imparted therein gas permeable membranes in combination with air spaces that will allow the free flow of gases between the cell culture compartments and the external environment. Furthermore an interconnecting passageway is provided between each compartment and between the cell culturing vessel and the external environment. The expandable vessel promotes the growth of large numbers of adherent or suspension cells by providing the volumes of nutrient medium and gaseous exchange.

BACKGROUND

1. Field of the Invention

The present invention relates generally to the cellular biological fieldand in particular, to an expandable cell culture vessel.

2. Technical Background

Culture conditions generally vary depending on the type of cells inculture and the purpose for culturing the cells. The cells may bederived from a number of sources, for example, bacteria, yeast, insectsand mammals and may be grown bathed in nutrient medium, in suspensionculture or adhered to a substrate. The cells may be used to produce adesired substance, or the cells themselves may be the product.

The ability to use the cells and/or the substances produced from thecell cultures, in part, is determined by the attributes of the vesselsupporting the cell culture. The vessel should not contribute tounwanted components in the cell products. As technology advances in thebiological field, advances in technological support such as, advances insupport equipment must keep pace in order to fully realize the benefitof this knowledge. Cell and gene therapy applications will require cellculture vessels that are able to maintain the strictest asepticenvironment, for example, with each cell culture vessel dedicated togrowing specific cells for a specific individual.

Currently, a major contributor to the overhead of manufacturingbiopharmaceuticals is the cost associated with maintenance,sterilization and validation of non-disposable bioreactors/vessels. Cellculture vessels must be developed to sustain the level of cleanlinessrequired without incurring this excessive expense or risking thepossibility of contamination.

Development of optimal process conditions for cell growth usually beginswith a single vessel growing thousands of cells, as opposed tomonitoring a large-scale system with billions of cells. It is importantto maintain the microenvironment of the cells in culture to enableconsistent cell performance. Progressing from the single vessel to thelarge-scale system is not straight-forward, since no simple vesselsystem exists that permits direct extrapolation of culture conditionsfrom the single vessel to the large-scale system.

Gas exchange between external and internal environments of the cellculturing vessel is necessary in order to sustain the metabolicrequirements of the cells in culture. In large-scale systems, specialconsideration must be given to gas exchange between the externalenvironment and in the nutrient medium within the vessel, since thesurface area to volume ratio goes down as the vessel volume increases.This decrease in surface area with increased volume limits the amount ofnutrient medium available for diffusion and limits the gas exchange.Spatial gradients can also occur in large-scale vessels, and remediessuch as sparging and agitation can lead to foaming of the nutrientmedium and also shear damage to the cells in culture.

A number of conventional cell culture systems utilize sheets of polymerto form bags. In U.S. Pat. No. 6,190,913, the polymer sheets are thickenough to withstand wave-like agitation in order to induce mixing andfacilitate the gas exchange necessary to ensure proper cultureconditions. This equipment requires maintenance and occupies spaceoutside of that needed for the cell culture vessel itself. Otherbag-like cell culture devices, for example, those disclosed in U.S. Pat.Nos. 4,945,203 and 5,736,398, are formed from polymer sheets that arevery thin, thus permitting gas exchange to occur through the polymersheet material without agitation or sparging. However, handlingunsupported, large scale bag vessels is cumbersome and unwieldy.

Alternatively, gas exchange between the external atmosphere and internalculture environment has led to the development of multi-layered highdensity cell culture vessels as described in, for example, commonlyowned U.S. application Ser. No. 11/433,859, the disclosure of which isincorporated herein in its entirety. The vessels described therein areassembled with gas permeable materials and enable these devices to meetthe oxygen requirements for cellular metabolism without sparging oragitation. These vessels have an increased surface area for cell growthas well as a suitably rigid structure to permit robotic handling.However, a limitation of these devices occurs because the rigidity thatenables robotic handling necessitates that the vessel volume remainsfixed, making modifications to culture conditions more problematic.

Thus, there is a need for disposable cell culture vessels which enablethe aseptic growth and maintenance of cells in culture utilizing adesign that is capable of being scaled from a small volume (<1 L) to alarge volume (>10 L) without modifying culture conditions. It would beadvantageous to have cell culture vessels which would simplify andreduce the space requirements to perform large scale cell cultureoperations; in particular, the variables added by perfusion, spargingand movement, as well as the mechanical accessories and equipment neededto perform these manipulations.

Furthermore, there is a need for cell culture vessels, capable of thenecessary gas exchange for the growth of cells, which allow forincreasing internal volumes of nutrient medium, thus permittingcontinual growth of multiplying numbers and sizes of cells. This vesselexpansion would allow for both the volume increase and augmentation ofthe nutrient medium during use without withdrawing the cells from theiraseptic environment for transfer to a vessel with greater capacity, thusreducing the risk for contamination. It would be advantageous to havesuch cell culture vessels enable the growth or maintenance of eitheradhesion dependent or suspension cells in culture. Also, the ability tostack the cell culture vessels would be beneficial in maintaining andexpanding large volumes of cells in culture allowing efficient spaceutilization and ease of handling. Furthermore, there is a need forcost-effective disposable cell culture vessels constructed usingoptically clear materials for monitoring the growth of cells which maybe easily assembled and efficiently utilized.

SUMMARY OF THE INVENTION

According to one embodiment of the present invention, a cell growthapparatus for efficient culturing of cells is disclosed. The cell growthapparatus comprises a number of compartments, each compartment isexpandable and comprises at least one gas permeable, liquid impermeablesurface, an interconnection or passageway between each compartment toprovide an integral vessel for cellular growth, a spacer to maintain gasexchange positioned between each compartment such that one or more airpockets or spaces are supported there-between.

According to another embodiment of the present invention, an externalsupport structure is provided to support the number of expandablecompartments, such that several expandable compartments may be stacked,handled and moved without collapsing the cell growth apparatus. Theexternal support structure reinforces the stability of the compositevessel, cell culture compartments.

In yet another embodiment of the present invention, the external supportstructure is also expandable to accommodate expanding compartments.

Cell culture vessels and methods using the cell culture vessels of thepresent invention will actively encourage diffusion and/or dispersion ofoxygen within large volumes of cell culture media through gas permeable,liquid impermeable components with increased surface to volume ratios.

Additional features and advantages of the invention will be set forth inthe detailed description which follows, and in part will be readilyapparent to those skilled in the art from the description or recognizedby practicing the invention as described in the written description andclaims hereof, as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are merely exemplary of theinvention, and are intended to provide an overview or framework tounderstanding the nature and character of the invention as it isclaimed.

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate one or moreembodiment(s) of the invention and together with the description serveto explain the principles and operation of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is best understood from the following detailed descriptionwhen read with the accompanying drawing figures. It is emphasized thatthe various features are not necessarily drawn to scale. In fact, thedimensions may be arbitrarily increased or decreased for clarity ofdiscussion.

FIG. 1 is a side view of the cell growth apparatus according to oneembodiment of the present invention.

FIG. 2 is a top view of one compartment of the cell growth apparatusaccording to another embodiment of the present invention.

FIG. 3 is a side view of one compartment of the embodiment shown in FIG.2.

FIG. 4 is a side view of the cell growth apparatus according to anotherembodiment of the present invention.

FIG. 5 is a side view of the cell growth apparatus according to anotherembodiment of the present invention.

FIG. 6 is a side view of the cell growth apparatus according to anotherembodiment of the present invention.

FIG. 7 is a top view of one compartment of the embodiment shown in FIG.6

FIG. 8 is a side view of the cell growth apparatus according to anotherembodiment of the present invention.

FIG. 9 illustrates exemplary shapes and porting of the cell growthapparatus of the present invention.

DETAILED DESCRIPTION

In the following detailed description, for purposes of explanation andnot limitation, exemplary embodiments disclosing specific details areset forth in order to provide a thorough understanding of the presentinvention. However, it will be apparent to one having ordinary skill inthe art that the present invention may be practiced in other embodimentsthat depart from the specific details disclosed herein. In otherinstances, detailed descriptions of well-known devices and methods maybe omitted so as not to obscure the description of the presentinvention.

Reference will now be made in detail to the present embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

An external view of an apparatus in accordance with one embodiment ofthe present invention is shown in FIG. 1. The apparatus 100 of thisembodiment is a high-density cell culturing device with verticallystacked compartments 114. The compartments 114 are confined by a topplaten 110 and a bottom platen 112 composed of a rigid material forvarious structural configurations having any size, shape, or dimensiondependent upon desirable volume capability. Each compartment 114 is madefrom a gas permeable material sealed together at the edges forming walls115. Gas permeable compartments 114/117 are collapsed; whereas gaspermeable compartments 114/118 are expanded to contain the nutrientmedium and growing cells. In this exemplary embodiment, the vessel 100is comprised of five compartments, though any number oflayers/compartments 114 may be stacked as long as the vessel isstructurally supported. Ports 101 within each compartment 114 adjoin tothe next compartment 114 in sequence and/or provide fluid communicationwith the external environment. Between each compartment is a spacermaterial 116 that maintains an area 103 for gas exchange. Thecompartments are therefore capable of being filled with cells andnutrient media to enclose an expandable volume of cell culture. Forexample, as the compartments fill with cells and nutrient media, thecompartment(s) swell in size from about 1 mm to about 2-5 mm in heightto enclose the growing volume of cells. The expansion of the compartment114 is dependent upon the enclosed volume of liquid, cells and media.

A top view of an exemplary embodiment of one gas permeable compartment114 of the present invention is illustrated in FIG. 2. The gas permeablecompartment 114 in this embodiment is expandable and comprises acompartment frame 202 that provides structural support for a gaspermeable compartment 204. The frame 202 itself is supportively rigidand lies outside of the sealed gas permeable material 204 forming asupportive perimeter. A port 101 is designated in one corner 208 of thegas permeable wall 115 which will interconnect with another similar gaspermeable compartment 114 in a cell culture stack. Although in thisembodiment, the port 101 is shown in the corner of the gas permeablewall 115 through the gas permeable material 204, ports 101 may belocated at any location requiring fluid communication into the gaspermeable compartments 114 from the external environment, between thegas permeable compartments 114 and/or to the external environment fromthe gas permeable compartments 114.

Shown in FIG. 3 is side view of one compartment 114 of the exemplaryembodiment shown in FIG. 2. A supportive compartment frame 202 islocated outside of the sealed edges 115 of the compartment. A spacermaterial 116 lies above and below the gas permeable material 204 tomaintain air spaces 103 for gases to circulate and diffuse through thegas permeable material 204. The spacer material 116 may be constructedas a planar sheet with features formed therein in order to maintain anair space 103 between gas permeable compartments or between gaspermeable compartments and other gas impermeable surfaces. An example ofthis spacer material is a 0.020 inch thick thermoformed polymer such aspolyethylene or polypropylene with rounded pinpoint-size featuresprotruding 0.010 inch from the planar surface in a regular pattern onone or both sides of the planar surface. On the other hand, the spacermaterial 116 may be any rigid or flexible support network that iscapable of maintaining the air space 103 between cell growthcompartments 114 to allow for gas diffusion through the air space 103and between the gas permeable material 204 and the external atmosphere.An example of such a flexible support network is a woven mesh. Theconstruction of the spacer material 116 may be of any composition, forexample, polyethylene, polypropylene, polyvinylchloride, polycarbonate,polystyrene, polyester, nylon or other suitable polymer or metal.Suitable metals may be, for example, aluminum, titanium stainless steelor the like. The spacer material may be of any configuration thatpermits at least a 0.001 inch air space 103 to form between each cellgrowth compartment 114. Further, any number of compartments 114 may bestacked together with filling and emptying inlets and outletsinterconnecting the compartments limited only by the ability of thecomposite vessel stack to maintain a stable structural conformation.Thus, the present invention can be utilized for adherent or suspensioncell culture to promote the growth of large numbers of cells throughoutthe expandable cell culture vessel 100.

When multiple compartments 114 are stacked, as shown in the exemplaryembodiment in FIG. 4, the ports 101 may be staggered for fluid toperfuse through each individual compartment 114 and into the nextcompartment in series within the five layered vessel 400. Also, theports 101 may provide entrance and/or exit points for media, fluids,analytical devices and the like. The accordion formation 404 between thetop platen 110 and bottom platen 112 including individual flexiblecompartments 114 formed there-between enables compression and/orexpansion of the all of the compartments 114 individually or as a unitdepending on the flexibility of each of the individual compartments 114,the rigidity of any of the compartment frames 202, the elasticity ofinterconnecting ports 101, and/or the pliability of the spacer material116 which lies between each cell growth compartment 114.

In another embodiment shown in FIG. 5, a large scale cell culture vessel500 with aligned ports 101. The cell culture vessel 500 is constructedof similar gas permeable materials 204 as in previously discussedembodiments; the gas permeable materials 204 are supported bycompartment frames 202, separated by air spaces 103 for gas exchange bythe spacer material 116 there-between where fill ports 101 allow fluidcommunication between each compartment 114. When the ports 101 arealigned, an access tube 520 may be inserted to direct flow of fluid intoeach port 101. In one aspect, the access tube 520 is a tube with holes522 corresponding spatially to each port 101 in the cell culture vessel500. The access tube 520 may be a separate unit as demonstrated in theillustration of FIG. 5 or may be integrally connected and rotated,separately interconnected within the cell culture vessel 500 to permitor restrict flow. Therefore, it would be possible to fill the funnelshaped top 524 of the access tube and seal off other ports 101 toselectively fill specified cell culturing compartments 114.

FIG. 6 illustrates one embodiment of a large scale cell culture vessel600. The vessel 600 includes flexible cell culturing compartments 614formed between the top platen 110 and the bottom platen 112. The gaspermeable materials 204 forming growth surfaces and/or walls of the cellculturing compartments 614 are secured along outer edges 603 of theperimeter of the compartment frame 202. Grommets or other supported holestructures 610 (also illustrated in a top view in FIG. 7) can bepositioned through the gas permeable materials 204, the spacer materialand the supportive compartment frame at each corner 611 and/or otherpositions around the perimeter of the cell culturing compartments 614.Support rods 612 which may be telescoping, run through the grommets 610at the corners 611 and/or other positions around the perimeter of thecell culturing compartment 614 of the stack of compartments and connectonto the rigid top platen 110 and the rigid bottom platen 112.Telescoping support rods are able to collapse or expand with changingvolumes within individual compartments or within the entire cellculturing vessel and thusly do not hinder the expanding or collapsing inany way. The support rods 6112 assist in providing structural support tothe flexible stack of gas permeable cell culturing compartments 614.

In another embodiment as demonstrated in FIG. 8, each cell culturingcompartment 114 between the top platen 110 and the bottom platen 112 isjoined by integral tubing 803 formed either by bonding the gas permeablematerial to form tubes or by attaching preformed tubing. A port 801 ofthe vessel 800 is included in the rigid top platen 110; however, theport 801 may be incorporated anywhere in a wall of the vessel to allowfluid into and out of the vessel. There may also be multiple portsfunctioning as either inlets or outlets for accessing one or multiplecompartments. The cell culturing vessel 800 is formed by sealing theperipheral edges 115 of two adjacent gas permeable materials 204 to formthe individual cell culturing compartments 114 with spacer material 116to form the air spaces or gaps 103 for gaseous exchange between theindividual compartments 114 as well as between the compartments and therigid external support platens 110/112. The tubing 803 interconnects theports 811 of each compartment 114; the length and the diameterdimensions of the tubing corresponds to the expansion capacity of theentire vessel, and the viscosity and/or measure of volumetric flow.Moreover, flow rate may be a factor for configuring the design of thevessel.

Although any size, shape or configuration of large scale vessel may beutilized, FIG. 9 illustrates some exemplary embodiments of vesselcompartment shapes. Each compartment 901/902/903/904 has ports 906 whichcan have the placement of the ports staggered on successive layers ofcompartments. The staggering of the ports 906 from one location toanother on successively stacked compartments prevents fluid from rushingthrough the vessel having multiple stacked compartments and permitscontrol of the speed and volume of fluid (media, cell, etc.) flowinginto each compartment and prevents the cells from pooling in onelocation within the compartment or the vessel as they settle. The arrowsdesignate the possible shifted positioning of the ports on successivelayers as illustrated by progressively darker shading of inlet/outletports 906. A slant 907 in positioning the layers of compartments of thevessel provides the capability of alternating sides by back and forthrocking in order to promote fluid removal. Alternatively, in compartment905 the ports may be composed of integral tubing 803 located in one ormore positions on the perimeter of the compartment 905.

Any material composition useful for culturing cells may be employed inmaking the compartments of the embodiments of the present invention. Thecompositions may be durable, flexible or semi-flexible material to allowexpansion volumes for cell growth. The composition must be capable ofcontaining a liquid volume and be gas permeable. Possible materials thatmay be employed to make the cell culture compartments include, but arenot limited to, polystyrene, polypropylene, polyethylene, polycarbonate,silicone rubber, fluoroethylenepropylene copolymer, as well ascopolymers and multilayers of these materials. Many of these materialsare transparent and may be used to make optically clear compartments.

Septa may also be integrally affixed to the body of the apparatus. Thesepta may take any form well known to those of skill in the artincluding a slit arrangement useful for blunt needles and as generallydescribed in WO02066595. Possible materials that may be employed inmaking the septa include natural and synthetic elastomeric materialsincluding, but not limited to fluoro-carbon rubber, butyl rubber,polychloroprene rubber, a silicone elastomer composite material,thermoplastic elastomer, medical grades of silicone rubber,polyisoprene, a synthetic isoprene, santoprene and fluoropolymerlaminate and combinations thereof. In a preferred embodiment, theelastomeric material is substantially nontoxic to cultured cells.Moreover, the cell culture compartment ports may be joined by a manifoldto allow access from a single port and the multiplicity of cell culturecompartments may be encased by an external structural support skeleton.Embodiments of the cell culture vessel may therefore be designed to beutilized when significant robotic manipulation is encountered.

The support structure may be made by any number of manufacturing methodswell known in the art. Injection molded polymer materials areparticularly useful in making the support structure, for example,polystyrene, polypropylene, polyethylene, polycarbonate, siliconerubber, fluoroethylenepropylene copolymer or combinations thereof. Oneadvantage of using polystyrene at a thickness of no greater than 2 mm isthat optical clarity through the support structure and through thecompartments is maintained. Therefore, cell cultures may be visuallymonitored from the external environment.

In utilizing the cell culturing apparatus of the present invention,various methods in the industry may be employed in accordance withaccepted cell growth culturing. Cells immersed in media are introducedto the vessel through any number of inlets/ports and may be drained viathe outlet(s)/port(s). The vessel is arranged such that thecell-containing media covers the cell growth surfaces (e.g. the gaspermeable, liquid impermeable surfaces). Advantageously, the cell growthapparatus is capable of being completely filled with media since the gaspermeable compartments in combination with the air spaces (as maintainedby the spacer material in a flexible/expanding configuration) provideuniform gas distribution to the cell growth surfaces. The spacer, of anymaterial composition, with any porosity or interconnecting arrangement,will further ensure the flow and exchange of gases between the interiorof the cell culture compartments and the external environment. Ifnecessary, the vessel may be placed within an area that maintains theappropriate temperature for the particular cells in culture. The cellculturing apparatus may be stacked together with similar cell culturingapparati such that a number of cell cultures are simultaneously grown.The cell culturing apparatus is situated such that the bottom platen ortray assumes a horizontal position. In the case of an adherent cellculture, the cell culturing apparatus can then be inverted to permit theculturing of cells on the opposite surface. Where only gas permeablematerials provide the peripheral surfaces for the cell culturingcompartments of the cell culturing apparatus, cell growth is enabled onupper and under sides of the compartment (opposing gas permeablesurfaces).

During the cell growth process, it may become necessary to extract theexhausted media and insert fresh media. As previously described, mediareplacement may be achieved through insertion of a canula, for example,through a septum attached to a port, or a port simply uncapped. Theconvenient construction of the vessel, however, allows the media and/orcells to be drained by opening an outlet port and replaced by directingthe media/cells into an inlet port. All of this may be conductedaseptically to avoid risk of contaminating the cultured cells. In thecase of attachment dependent cells, once the cells are ready forharvesting, a chemical additive such as trypsin, EDTA and/or other cellrelease substances may be added to the vessel through the septum. Thesesubstances have the effect of releasing the cells from the vesselsurfaces. The cells are then harvested from the apparatus.Alternatively, the cells may be released from the surface mechanically,by gentle folding or stretching of the gas permeable surfaces. Thisenables the cells to be harvested without chemical contribution ordamage to the cell structure. Cells in suspension culture may simply beexpelled from the vessel along with the nutrient medium for furtherprocessing.

As discussed, the embodiments of the present invention are for exemplarypurposes only and not limitation. The vessels may be stacked adjacent toone another with platens in direct contact. A diversified network ofsupports/platens, intersecting and/or alternating gas permeablecompartments with spacer material to allow for any number of cellculture compartments and air spaces can be utilized in the embodimentsof the present invention so long as they are capable of permitting gasexchange of the cell growth compartments with the external environment.Uniform gaseous distribution throughout the cell culture vessel cantherefore be achieved. Furthermore, the apparatus of the presentinvention may utilize horizontal or vertical designs having surfacesarranged for uniform gaseous distribution to cell growth areas. Forconvenience, hinged platens may even swing into place to supportadditional compartments. Clamps may also hold unused compartments closedand rolled-up next to the compartments in use. The flexibility of thevessel components and surfaces therefore provide a variety of optionsfor utilization and design.

The uniformity of conditions for attachment dependent cellular growthmay include a determined media volume per unit surface area. Though thedetermined ratio of volume per unit surface area has previously beenknown within a confined range of about 0.25-0.5 ml/cm², the ratio is nolonger limiting due to the direct access of the cells to gaseousexchange via the gas permeable material surrounding the cells. Whileefficient use of media is still preferable, any volume of media may beutilized in an apparatus of this invention, the apparatus of which maybe any size and/or take any shape suitable for the specified cell growthapplication. Further, the enhanced capabilities of the present inventionmay be incorporated in combination with cell growth chambers ofstandardized or conventionally-sized containers. As stated previously,however, the height and dimensions for cellular growth are no longerrestricted so long as an expandable area is included for the growth ofcells.

The embodiments of the present invention may be modified to take theshape of any device, container, apparatus, vessel, or flask currentlyused in industry. Specifically, cylindrical or alternative vessels mayutilize gas permeable materials (internal to the vessel) in combinationwith air spaces to provide an improved culturing environment for thegrowth of cells. Inclusive in an integral vessel construction areimprovements that also incorporate a woven mesh as a spacer material toallow construction of an expansive flexible container. The ability tosparge, perfuse, agitate, or otherwise induce mixing also remainpossible with the present invention.

As presented, the multiple embodiments of the present invention offerseveral improvements over standard vessels currently used in industry.The improved cell culture devices remarkably enhance the number of cellsthat are capable of being cultured in the volume enclosed by traditionalcell culture vessels. The various benefits are attributable to themulti-layered arrangement of gas permeable compartments assembled into aunitary vessel and the semi-rigid construction of those layers. The gaspermeable compartment construction alternating with spacer material thatcreates gas exchange spaces permits continual growth of cells andaugmentation of nutrient media volume without necessitating transfer toa larger vessel, thus reducing the risk of contamination. The inventiontherefore provides an expansion component that is incorporated in theimprovement of the cell culturing vessel. The gas permeable compartmentsfurther make oxygen and other gases from the external environmentavailable to the internal contents of the apparatus. Specifically,gaseous exchange with the nutrient media is conducive to an evendistribution of cell growth when gas permeable materials are utilized inthe construction of the cell growth compartments. The cell growthapparatus is capable of fully utilizing its capacity by allowing cellsaccess to optimal volumes of nutrient media and direct oxygenation viathe air spaces without the need for cumbersome, space-occupyingancillary equipment. The previously unforeseen benefits have beenrealized and conveniently offer advantages for exponential cell growth,including a flexible cell culturing apparatus for maintaining gaseousexchange between the internal cell growth areas and external environmentas well as an expandable cell culturing apparatus that is designed foreasy handling, storage, and accessibility.

As exemplified, the apparatus may include any unitary structure, vessel,device or flask with the capacity to integrally incorporate gaspermeable compartments in combination with spacer materials insuccessive orientation. The invention being thus described, it would beobvious that the same may be varied in many ways by one of ordinaryskill in the art having had the benefit of the present disclosure. Suchvariations are not regarded as a departure from the spirit and scope ofthe invention, and such modifications as would be obvious to one skilledin the art are intended to be included within the scope of the followingclaims and their legal equivalents.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A cell growth apparatus comprising: a plurality of compartmentshaving expandable walls comprising at least one gas permeable, liquidimpermeable surface; a spacer material positioned between each of thecompartments to form a gas exchange area there-between; aninterconnecting passageway in fluid communication with each of thecompartments and the external environment.
 2. The cell growth apparatusaccording to claim 1, wherein each compartment comprises opposing gaspermeable, liquid impermeable surfaces.
 3. The cell growth apparatusaccording to claim 1, wherein each compartment comprises a plurality ofgas permeable, liquid impermeable surfaces which form the expandablewalls of the compartment.
 4. The cell growth apparatus according toclaim 1, wherein the gas permeable, liquid impermeable surfaces areselected from the group consisting of polystyrene, polypropylene,polyethylene, polycarbonate, silicone rubber, fluoroethylenepropylenecopolymer and a combination thereof.
 5. The cell growth apparatusaccording to claim 1, wherein the spacer material is selected from thegroup consisting of polyethylene, polypropylene, polyvinylchloride,polycarbonate, polystyrene, polyester, nylon, aluminum, titanium,stainless steel and a combination thereof.
 6. The cell growth apparatusaccording to claim 1, wherein the spacer material is selected from thegroup consisting of a woven mesh and a planar sheet comprisingprotruding support features.
 7. The cell growth apparatus according toclaim 1, further comprising a support structure external to thecompartments.
 8. The cell growth apparatus according to claim 7, whereinthe support structure comprises a compartment frame perimetricallysurrounding each of the compartments for supporting the gas permeable,liquid impermeable surfaces.
 9. The cell growth apparatus according toclaim 7, wherein the support structure comprises a top platen and abottom platen confining the plurality of compartments there-between. 10.The cell growth apparatus according to claim 7, wherein the supportstructure is optically transparent.
 11. The cell growth apparatusaccording to claim 9, wherein the support structure further comprises atleast one rod inserted through a supported hole in at least one of thecompartments and attached to the top platen and the bottom platen. 12.The cell growth apparatus according to claim 10, wherein the rod istelescoping to form an expandable support structure.
 13. The cell growthapparatus according to claim 1, wherein the interconnecting passagewaycomprises ports in the gas permeable, liquid impermeable surface of eachcompartment.
 14. The cell growth apparatus of claim 13, wherein theports are aligned between two adjacent compartments.
 15. The cell growthapparatus of claim 13, wherein the ports are staggered between twoadjacent compartments.
 16. The cell growth apparatus of claim 13,wherein the interconnecting passageway comprises tubing which connectsthe port of one compartment to the port of another compartment.
 17. Thecell growth apparatus of claim 13, further comprising an access tubehaving holes which correspond spatially to the ports in the gaspermeable, liquid impermeable surface of each compartment.
 18. The cellgrowth apparatus according to claim 1, wherein the compartments areoptically transparent.
 19. A cell growth apparatus comprising: aplurality of compartments having expandable walls comprising at leastone gas permeable, liquid impermeable surface; a flexible spacermaterial positioned between each of the compartments to form a gasexchange area there-between; an interconnecting passageway in fluidcommunication with each of the compartments and the externalenvironment; and an expandable support structure external to thecompartments to stabilize the cell growth apparatus.
 20. The cell growthapparatus according to claim 19, wherein the compartments are opticallytransparent.